1. Field of Invention
The present invention relates to gaskets, and more particularly to a sealing device for a thermal device, which is adapted to fasten with a door of the thermal device to sealedly enclose the thermal chamber therein.
2. Description of Related Arts
A thermal appliance, such as oven, generally generates heat within a thermal chamber therein, wherein the thermal appliance comprises a container body and a door pivotally mounted to the container body to form the thermal chamber within the container body and the door. In order to prevent the heat from escaping the thermal chamber through the gap between the container door and the door, a gasket is typically used to mount on the door to seal the gap.
A conventional gasket is made of rubber and is securely fastened at the perimeter of the door such that when the door is pivotally folded to close the container body, the gasket is sealedly sandwiched between the door and the container body so as to sealedly enclose the thermal chamber. However, the conventional gasket has several drawbacks.
Since the gasket is made of rubber, the gasket provides a predetermined elasticity to seal the gap between the container body and the door. However, since the thermal appliance generates a relatively high temperature within the thermal chamber, such as 350° C. to 500° C., the rubber made gasket will gradually be deformed after a period of time usage. Once the elasticity of the gasket is reduced, the gasket cannot effectively seal the gap between the container body and the door such that the heat is started to escape from the thermal chamber to outside through the gap. Therefore, the gasket must be replaced after of period of time usage.
U.S. Pat. No. 5,107,623, owned by Weil, generally suggests an improved gasket, as shown in FIG. 1, which comprises an outer jacket 1A woven around an elongated core 1B and a plurality of fasteners 1C spacedly formed along the outer jacket 1A, wherein each of the fasteners 1C has a base portion 11C disposed between the outer jacket 1A and the elongated core 1B and an engagement portion 12C extended outwardly from the base portion 11C through the outer jacket 1A. Therefore, the gasket is adapted to mount at the perimeter of the door by respectively inserting engagement portion 12C of the fasteners 1C into fastening holes spacedly formed along the perimeter of the door.
Accordingly, the elongated core 1B is made of metal wire to retain the shape of the outer jacket 1A. However, since the base portion 11C of each of the fasteners 1C is mounted between the elongated core 1B and the outer jacket 1A, the fasteners 1C cannot substantially support the total weight of the elongated core 1B and the outer jacket 1A after a period of time usage. Therefore, the outer jacket 1A will be gradually deformed due to the weight of the elongated core 1B, as shown in FIG. 1. In other words, the outer jacket 1A will be torn easily along the split that the engagement portion 12C of the fastener 1C extended therethrough. Such gasket losses the heat resistance ability when the outer jacket 1A is broken.
In addition, the manufacturing process of such gasket is complicated since each of the fasteners 1C must be precisely mounted along the gasket at a position that the base portion 11C of each of the fasteners 1C is sandwiched between the outer jacket 1A and the elongated core 1B. Therefore, the complicated structure of such gasket not only increases the manufacturing cost thereof but also is disadvantage in practice use.